RU2264543C2 - Housing of cellular element, carrier of catalyst converter with such housing and method of manufacture of catalyst converter with such carrier - Google Patents

Abstract

FIELD: transport engineering.

SUBSTANCE: invention can be used in exhaust systems of internal combustion engines. Claim contains description of housing for cellular element with tubular casing having inner wall. To prevent nondetachable connection of tubular casing with cellular element it has passive film at least on some section of its inner wall. Description of method of manufacture of carrier of catalyst converter with cellular element and housing proposed by invention is also given in claim. Carrier of catalyst converter manufactured using proposed method prevents thermal stresses between cellular element and tubular casing and provides possibility of soldering, including vacuum soldering.

EFFECT: provision of compensation for difference in values of thermal expansion of cellular element and tubular casing.

28 cl, 4 dwg

Description

The present invention relates to a housing, in particular a tubular housing, for a honeycomb element, to a catalyst carrier with such a housing, and also to a method of manufacturing a catalyst carrier with such a housing. Such honeycomb cells are mainly used as carriers of a catalytic converter in exhaust gas (exhaust) systems generated by the operation of internal combustion engines (ICE), primarily automobile engines.

WO 99/37896 describes a method for manufacturing a honeycomb element enclosed in a tubular casing. Due to differences in the properties of the materials from which they are made, as well as due to differences in their working temperatures, the cell element and the tubular casing have different thermal expansion characteristics. Therefore, they seek to avoid the rigid connection of the honeycomb with the tubular casing at least at the end portion of the honeycomb, or in any case in certain distinct areas. For this reason, described in the application WO 99/37896, enclosed in a casing, the honeycomb element is equipped with a sleeve that can be put on it, which, despite technological deviations from the nominal sizes and shapes of the tubular casing and honeycomb, should prevent the formation of solder joints directly between the honeycomb element and a tubular casing at least at the end portion of the honeycomb element. The use of such a sleeve can significantly reduce the mechanical stresses caused by heating between the tubular casing and the honeycomb element, however, it leads to an increase in production costs.

From the prior art, there are further known means for preventing the interconnection of metal surfaces during high-temperature processing (as, for example, during sintering or soldering). The composition of these funds includes mainly small ceramic particles, a binder, as well as a certain amount of diluents and solvents. The binder, as well as the diluent and solvent, begin to disappear even at relatively low temperatures. In the manufacture of catalytic converter carriers, the tubular casing is connected to the housing preferably in vacuum, while the tendency of such agents to volatilize their constituent components, which, among other things, can contaminate the entire system, makes it difficult to maintain the required vacuum.

Based on the foregoing, the present invention was based on the task of developing a housing for a honeycomb element, which to compensate for differences in the thermal expansion of the honeycomb element and the tubular casing would selectively make permanent connections between them in locally limited areas and would ensure long-term fixation of the honeycomb , for example, in the exhaust system, and the task was also to develop a method of manufacturing a catalyst carrier with such a body mustache.

To solve the first of these problems, the invention proposes a housing for a honeycomb element having a tubular casing with an inner wall, which has a passivating film in at least one section of its inner wall to purposefully prevent its integral connection with the honeycomb element.

The passivating film has extremely high heat resistance and prevents the formation of any one-piece connection between each other mutually contacting metal surfaces. The area where the passivating film is located is located in the place of the tubular casing, where during the subsequent operation of the catalytic converter carrier it is necessary to ensure the possibility of relative movement of the honeycomb element and the tubular casing in order to avoid the occurrence of mechanical stresses caused by heating. The preferred location for this section is the end zone, in which a stream of hot exhaust gases flows onto the catalyst carrier. However, in the same way it is possible to prevent the formation of one-piece joints in areas located further downstream.

The passivation film due to its heat-insulating properties further prevents the transfer of heat from the honeycomb element to the tubular casing. The presence of a similar property in a passivating film is especially important, for example, in the case when, after starting the car engine, it is necessary to warm up the catalytic converter to an operating temperature at which the effective exhaust gas neutralization begins due to the catalytic conversion of their components in a minimally short time interval .

According to one embodiment of the housing of the invention, the passivating film is formed by a surface oxide layer. Oxides and, above all, metal oxides have high heat resistance and, as a result, interfere with the interconnection of contacting metal surfaces. A particular advantage also lies in the possibility of simple oxidation of the components of the material from which the tubular casing is made, which eliminates the need for additional material to form a passivating film. A similar metal oxide layer can also be obtained, for example, by simply roughening the inner wall of the tubular casing in its corresponding section.

According to a further embodiment of the housing according to the invention, the passivating film is formed by a layer of a deposited ceramic coating, in particular aluminum oxide. Ceramic particles have particularly high forces of mutual attraction and extremely high thermodynamic stability. The ceramic layer can also be applied from titanium oxide or magnesium oxide.

In accordance with a further embodiment, the passivating film is in the form of an annular band closed around the perimeter. In this case, the formation of solder joints between the tubular casing and the honeycomb element around the entire circumference of the tubular casing is prevented on such an annular portion, and it is possible to compensate for differences in the thermal expansion of the tubular casing and the honeycomb element.

In that case, if the casing is oval or elliptical in cross section, then according to the next embodiment, the passivation film is preferably located on that portion of the tubular casing that has a larger radius of curvature. The oval shape of the body must be given, for example, in the case when, when incorporating the support of the catalytic converter together with its body, it is necessary to take into account certain spatial conditions at a given location in the exhaust system. As experience shows, one-piece joints are preferably performed on those surfaces of such a casing that have a smaller radius of curvature, and accordingly prevent the formation of such compounds on rounded surfaces of the casing using a passivating film. It is advisable to use the passivating film on the rounded surfaces of the oval or elliptical shape primarily in addition to the passivating film possibly provided on the side of one or both ends of the honeycomb element.

According to another embodiment, the axial length of the passivating film is from 5 to 50 mm. Varying the axial extent of the passivating film within the specified limits allows you to precisely match its axial length for the specific purpose of using the housing for the honeycomb element according to the invention. So, for example, when placing the housing of the honeycomb element relatively close to the internal combustion engine or with significant differences in the thermal expansion of the honeycomb element and the tubular casing, the axial length of the passivating film is increased.

In a most preferred embodiment, the thickness of the passivating film is from 30 to 120 microns. A passivating film with a thickness varying within the indicated limits provides, first of all, effective compensation for deviations due to manufacturing tolerances from the nominal sizes and shapes of the honeycomb element and the tubular casing in their assembled state.

According to a further embodiment, the passivating film is formed by a ceramic coating layer, and a bonding layer is provided between the tubular casing and the applied ceramic coating layer. Such a bonding layer is preferably provided primarily when the ceramic layer is subjected to high dynamic loads. The bonding layer provides strong and durable adhesion of the ceramic layer to the metal surface of the tubular casing.

Before assembling the tubular casing with the honeycomb element, the passivation film on the inner surface of the tubular casing is most preferably coated with a layer of solder. As already mentioned above, the passivating film prevents the formation of solder joints between the honeycomb element and the tubular casing. However, when performing a honeycomb element, for example, from a plurality of layers formed by coiling and / or stacking metal sheets onto a passivating film, the solder allows soldering of the ends of adjacent metal sheets to each other. The connection between the ends of the metal sheets helps to prevent jitter or vibration of the end sections of the metal sheets and increase the service life of such a honeycomb element. The interconnection by soldering of all adjacent metal sheets at their end sections ensures the implementation of the solder layer, which covers the passivating film, in the form of an annular layer closed around the perimeter.

The invention also provides a catalyst carrier having a housing and a honeycomb member disposed therein. The honeycomb element consists of metal sheets, which are structured or profiled at least in certain areas so that they form channels for exhaust gases in the honeycomb element. According to the invention, such a catalyst carrier is characterized in that the tubular casing at least partially covers the honeycomb element and is connected to the honeycomb element in at least one separate axial section, and the catalyst carrier housing is made in the form of the housing of the invention described above. The permanent connection of the honeycomb element with the tubular casing only in locally limited areas can significantly increase the service life of the catalyst carrier.

In one embodiment of the catalyst carrier of the invention, a passivating film, which can be formed by a ceramic coating layer, is most preferably located near the end of the honeycomb element. The carrier of the catalytic converter when it is installed in the exhaust system in a position in which its ceramic-coated portion is facing the flow of hot exhaust gases, provides the most effective compensation for differences in the thermal expansion of the tubular casing and the honeycomb caused by high thermal load in the exhaust system Og.

According to yet another embodiment of the catalyst carrier of the invention, the radially outer end portions of the metal sheets of the honeycomb element abut against a passivating film, which can be formed by a ceramic coating layer. Due to this, it is possible to reduce vibration or jitter of these radially external end portions of the metal sheets. Said end portions of metal sheets adjacent to the passivating film are most preferably permanently connected to each other. In this case, the catalytic converter carrier has a long service life even when exposed to extremely high dynamic loads.

According to another embodiment of the catalyst carrier of the invention, the honeycomb element is connected to the tubular casing by soldering, preferably by vacuum brazing.

The invention also provides a method of manufacturing a catalyst carrier having a honeycomb element and a tubular casing. The honeycomb element consists of metal sheets, which are structured or profiled at least in certain areas so that they form channels for exhaust gases in the honeycomb element. The tubular casing, in turn, has an inner wall and at least partially covers the honeycomb element, and is also connected by soldering to the honeycomb element in at least one separate axial section. The tubular casing in at least one portion of its inner wall has a passivating film to specifically prevent the formation of a solder joint with the honeycomb element. Proposed in the invention a method of manufacturing a carrier of a catalytic converter is characterized by the presence of the following stages.

At the first stage, a tubular casing is made, after which a passivating film is obtained on the inner wall of the tubular casing in at least one portion thereof. In this area during the subsequent soldering process, it is necessary to prevent the formation of a solder joint between the tubular casing and the honeycomb element. Preferably, this section is located near the end of the honeycomb element when it is placed in a tubular casing. Then, at least on certain sections of the inner wall of the tubular casing, solder is applied.

At the same time or sequentially with the manufacture and preparation of the tubular casing according to known technology, a honeycomb element is formed by collecting metal sheets into a bag and / or rolling them into rolls, which are structured or profiled at least in some sections so that they form flow-through elements for spent cells in the honeycomb gas channels. Then the finished honeycomb element is placed in a tubular casing. After this, solder joints are created. The method described above makes it possible to fabricate a catalyst carrier, which (carrier), on the one hand, has a durable connection between the honeycomb element and the tubular casing, and, on the other hand, allows compensation for differences in the thermal expansion of the honeycomb element and the tubular casing. However, during the soldering process, no vapors and gases are formed that can adversely affect the formation of soldered joints, carried out mainly in a vacuum.

According to one embodiment of the method of the invention, a passivating film is obtained by selectively, spatially limited heating of at least one portion of the tubular casing. In accordance with this option, the portion of the inner wall of the tubular casing is heated to a certain temperature and, if necessary, maintained at it in order to ensure the occurrence of diffusion processes in the material, as well as on the inner wall of the housing. In this regard, it is advisable to use primarily ferritic, containing aluminum and chromium materials, which are heated to temperatures above 1100 ° C. In this case, metal atoms, primarily aluminum, diffuse from the inside into the surface layers of the inner wall of the tubular casing and, reacting with oxygen present in the environment, form the necessary passivating film. Accordingly, a passivating film can be obtained without the use of filler material.

Moreover, the above portion of the inner wall of the tubular casing is most preferably heated by induction heating. During induction heating, spatially limited eddy currents are induced, which, due to the electrical resistance of the material, heat the treated area. The induction heating method not only allows you to heat the surface in a precisely limited area, but can also be used in line production for the manufacture of high-rate catalytic converters.

According to yet another embodiment of the method of the invention, when producing a passivating film, at least one portion of the inner wall of the tubular casing is blown with a stream of oxygen-containing gas. This ensures the presence of a sufficient number of oxygen molecules at the inner wall of the tubular casing necessary for the formation of a surface oxide layer. In this embodiment, thus, it is possible to intensify the formation of a passivating film.

In addition, when receiving a passivating film, the tubular casing outside of at least one portion of its inner wall is most preferably blown with a stream of inert gas, especially argon. Inert gas, because it does not react with metal atoms that make up the material of the tubular casing, and displaces air oxygen, while preventing the formation of an oxide layer.

In a further embodiment of the method of the invention, a passivating film is obtained by chemical treatment of at least one portion of the inner wall of the tubular casing. To this end, the specified portion of the inner wall of the tubular casing is treated with a chemical reagent, providing the formation of a surface oxide layer. This embodiment of the method proposed in the invention is expediently used primarily in the treatment of tubular casings made with extremely small manufacturing tolerances on their internal dimensions, which determine the possibility of placing cellular elements covered by them in them. In this embodiment, there is no longer a need for heat treatment of the tubular casing, which avoids the possible deformation of the tubular casing associated with it, which may occur during heat treatment of the tubular casing without a honeycomb inserted therein.

According to a further embodiment of the method according to the invention, a passivating film is obtained by applying at least one portion of the inner wall of the tubular casing of a ceramic coating layer, in particular aluminum oxide.

In a further preferred embodiment of the method of the invention, a bonding layer is applied to at least one corresponding portion of the inner wall of the tubular casing before applying the ceramic coating layer. Such a bonding layer provides the strongest adhesion of the ceramic layer to the tubular casing. In a preferred embodiment, to perform such a bonding layer, a material should be used that does not contain any volatile components that would otherwise impair the quality of the brazed joints performed during the subsequent soldering process.

When applying a passivating film in the form of a layer of ceramic coating it is most preferable to create it on a tubular casing by flame spraying. The method of flame spraying provides a particularly uniform distribution of the ceramic layer along the inner wall of the tubular casing, and thereby avoids uneven pressing of adjacent metal sheets to the tubular casing.

According to another embodiment of the method according to the invention, before applying the solder to the inner wall of the tubular casing, in particular to a passivating film, an adhesive composition is applied to apply a layer of solder. The purpose of this adhesive composition is to fix the solder powder in those places of the tubular casing, where during the subsequent soldering process, solder joints should form. The application of the adhesive composition to the ceramic layer also ensures the accumulation of powder solder in that area of the honeycomb element, in which it is undesirable to connect it to the tubular casing. In this section, such a solder layer is necessary for subsequent connection between each other by soldering adjacent metal sheets of the honeycomb element.

In a further embodiment of the method of the invention, powder solder is applied to the end of the cell during the placement of the honeycomb element in the tubular casing or upon completion of this process. In this case, a connection is made between each other by soldering the end sections of the metal sheets near the end of the honeycomb element and thereby increases the service life of the catalytic converter made in this way.

In accordance with a further embodiment of the method of the invention, a passivating film is obtained by roughening the inner wall of the tubular casing in at least one portion thereof. Moreover, the roughness of the inner wall of the tubular casing is most preferably imparted by sandblasting and / or by painting. By roughening the inner wall of the tubular casing, unexpectedly, it is possible to prevent wetting of this roughened portion with molten solder, thereby avoiding the formation of an integral connection between the honeycomb element and the tubular casing. In this embodiment, thus, obtaining a passivating film in the most economical way.

Below proposed in the invention the catalyst carrier and the method of its manufacture are described in more detail on the example of the most preferred embodiments of the invention with reference to the accompanying drawings, which show:

figure 1 - image in axonometric projection of a tubular casing and a honeycomb element included in the composition proposed in the invention of the carrier of the catalytic converter,

figure 2 is an end view of the proposed invention, the carrier of the catalytic converter Assembly,

figure 3 is a schematic illustration of a layered structure near the proposed invention in the housing and

figure 4 is a sectional view of an oval body with a honeycomb element and a passivating film.

Figure 1 shows a honeycomb element 4 having an end face 12. This honeycomb element consists of a plurality of layers rolled into a roll and / or packaged metal sheets 9. During assembly, the honeycomb element 4 is placed in a tubular casing 1. The tubular casing 1 has an inner wall 2 with a passivating film 3 in section 14. This section 14 has an axial length of 5 and in the assembled state of the catalyst carrier is located near the end 12 of the honeycomb element 4. An additional layer of solder is applied to the inner wall of the tubular casing in section 14.

After placing the honeycomb element 4 in the tubular casing 1, they are interconnected due to the formation of soldered joints. At the end of the soldering process, the honeycomb element 4 is inseparably connected in a separate section 11 with the tubular casing 1. The passivation film 3 located in the region 14 prevents the connection of the honeycomb 4 with the tubular casing 1, which compensates for differences in the values of their thermal expansion in this section 14 The solder layer 7 serves to connect metal sheets 9 to each other.

In Fig.2 proposed in the invention, the catalyst carrier is shown from the side of its end. The tubular casing 1 covers a plurality of metal sheets 9, which abut against the tubular casing 1 with their radially outer end portions 13. Among the layers of metal sheets there are smooth and corrugated metal sheets 16, which are arranged so that they form channels 10 for exhaust gases in the honeycomb element .

Figure 3 schematically shows the structure of the housing according to the invention for a honeycomb element depicting the sequence of different layers (3, 6, 7) on a portion 14 of the inner wall of the tubular casing 1. On the inner wall 2 of the tubular casing 1 is a bonding layer 6, which provides strong adhesion of the passivating film 3 with the tubular casing 1. The passivating film 3 has a thickness of 8, which can vary within certain limits depending on the requirements of the catalytic neutron carrier catalysts. On top of the passivating film 3, an additional layer of solder 7 is located, which ensures the connection between the end sections 13 of adjacent metal sheets 9.

4, a sectional view schematically shows an oval tubular casing 1 with a honeycomb element 4 and a passivating film 3. A honeycomb element consists of a plurality of layers rolled up and / or stacked metal sheets 9, which are structured or profiled at least in separate sections so that they form channels flowing for the exhaust gas in the honeycomb element. The honeycomb element 4 has a plurality of such channels 10, which are bounded by smooth and / or corrugated metal sheets 16, and enclosed in a tubular casing 1. The tubular casing 1 has an inner wall 2 with a passivation film 3 in section 17. In the section 17, according to which the invention the formation of a solder joint is undesirable, the oval or elliptical tubular casing 1 has a larger radius of curvature.

The catalytic converter carrier manufactured by the method of the invention and having the inventive design makes it possible to compensate for differences in the thermal expansion of the honeycomb element and the tubular casing, while the manufacture of such a catalytic converter carrier by the method proposed in the invention ensures an optimal course of the brazing process and, above all, the vacuum brazing process solder.

Claims (28)

1. A housing for a honeycomb element (4) having a tubular casing (1) with an inner wall (2), characterized in that the tubular casing (1) for purposefully preventing its integral connection with the honeycomb element (4) has at least one section (14) of its inner wall (2) passivating film (3). 2. The housing according to claim 1, characterized in that the passivating film (3) is formed by a surface oxide layer. 3. The housing according to claim 1, characterized in that the passivating film (3) is formed by a layer of deposited ceramic coating primarily from aluminum oxide. 4. The housing according to any one of claims 1 to 3, characterized in that the passivating film (3) has the shape of an annular band closed around the perimeter. 5. The housing according to any one of claims 1 to 3, characterized in that the tubular casing (1) is oval or elliptical in cross section, and the passivation film (3) is located on that section (17) of the tubular casing that has a larger radius of curvature . 6. The housing according to any one of claims 1 to 5, characterized in that the axial length (5) of the passivating film (3) is from 5 to 50 mm. 7. The housing according to any one of claims 1 to 6, characterized in that the thickness (8) of the passivating film (3) is from 30 to 120 microns. 8. The housing according to any one of claims 3 to 7, characterized in that the passivating film (3) is formed by a layer of ceramic coating, while between the tubular casing (1) and the layer of deposited ceramic coating (3) a bonding layer (6) is provided. 9. The housing according to any one of claims 1 to 8, characterized in that the passivating film (3) is coated with a solder layer (7). 10. The housing according to claim 9, characterized in that the solder layer (7) with which the passivating film (3) is coated is made in the form of an annular layer closed around the perimeter. 11. The catalyst carrier having a housing and a honeycomb element (4) of metal sheets (9), which are structured or profiled at least in certain areas so that they form flow paths for exhaust gases (exhaust gas) in the honeycomb element (4) channels (10), characterized in that the tubular casing (1) at least partially covers the honeycomb element (4) and at least on one separate axial section (11) is inseparably connected to the honeycomb element (4), and the carrier housing of the catalytic converter executed in the form of the housing according to any one of claims 1 to 10. 12. The catalyst carrier according to claim 11, characterized in that the passivating film (3) is located near the end face (12) of the honeycomb element (4). 13. The catalyst carrier according to claim 11 or 12, characterized in that the radially outer end portions (13) of the metal sheets (9) of the honeycomb element (4) are adjacent to the passivating film (3). 14. The catalyst carrier according to claim 13, characterized in that said end portions (13) adjacent to the passivating film (3) are inseparably interconnected. 15. The catalyst carrier according to any one of claims 11-14, characterized in that the honeycomb element (4) is connected to the tubular casing (1) by soldering, preferably by vacuum brazing. 16. A method of manufacturing a catalytic converter carrier having a honeycomb element (4) from metal sheets (9) that are structured or profiled at least in some areas so that they form exhaust gases (exhaust gas) in the honeycomb element (4) channels (10), as well as having a tubular casing (1) with an inner wall (2), which at least partially covers the honeycomb element (4) and which is connected to the honeycomb element by at least one separate axial section (11) 4), while being tubular the first casing (1) in at least one portion (14) of its inner wall (2) has a passivating film (3) for purposefully preventing the formation of a solder connection with the honeycomb element (4), characterized in that a tubular casing (1) is made, on the inner wall (2) of the tubular casing (1) in at least one of its sections (14), on which it is necessary to prevent the formation of a solder joint between the tubular casing (1) and the honeycomb element (4), a passivating film (3) is obtained, at least on individual sections of the inner wall (2) tr solder casing (1) is deposited, according to known technology, a honeycomb element (4) is formed, collecting metal sheets (9) into a bag and / or rolling them into rolls, which are structured or profiled at least in some sections so that they form the honeycomb element (4) the exhaust gas channels (10) for the exhaust gas, the honeycomb element (4) are placed in the tubular casing (1) and solder joints are created. 17. The method according to clause 16, wherein the passivating film (3) is obtained by selectively spatially limited heating of at least one area (14). 18. The method according to 17, characterized in that the plot (14) is heated by induction heating. 19. A method according to any one of claims 16-18, characterized in that upon receipt of the passivating film (3), at least one portion (14) is blown with a stream of oxygen-containing gas. 20. A method according to any one of claims 16-19, characterized in that upon receipt of the passivating film (3), the tubular casing (1) outside of at least one portion (14) is blown with an inert gas stream, in particular argon. 21. The method according to clause 16, wherein the passivating film (3) is obtained by chemical treatment of at least one area (14). 22. The method according to p. 16, characterized in that the passivating film (3) is obtained by applying at least one section (14) of the inner wall (2) of the ceramic coating layer, primarily aluminum oxide. 23. The method according to p. 22, characterized in that before applying a layer of ceramic coating at least one area (14) apply a binder layer (6). 24. The method according to item 23 or 24, characterized in that the passivating film (3) is applied in the form of a layer of ceramic coating created on the tubular casing (1) by flame spraying. 25. The method according to any one of paragraphs.16-24, characterized in that before applying the solder to the inner wall (2) of the tubular casing (1), especially to the passivating film (3), an adhesive composition is applied to apply the solder layer (7) . 26. The method according to any one of paragraphs.16-25, characterized in that in the process of placing the honeycomb element (4) in the tubular casing (1) or at the end of this process, powder solder is applied to the end face (12) of the honeycomb element (4). 27. The method according to clause 16, wherein the passivating film (3) is obtained by roughening the inner wall (2) in at least one of its sections (14). 28. The method according to item 27, wherein the roughness of the inner wall is imparted by sandblasting and / or by painting.

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